The present invention relates to a suture anchor for attaching suture to body tissue, such as bone.
Suture anchors are used in surgery, in particular in orthopedic surgical operations for placing a part of the suture in and attaching it to a bone, wherein the part of the suture that is not attached, most commonly two parts projecting from the bone, can be further used e.g. for connecting detached connective tissue, such as ligament, to the bone. To place the suture anchor into a bone, a hole is made in the bone, e.g. by drilling, into which hole the suture anchor and a part of the suture is inserted, wherein the object of the suture anchor is to keep the suture firmly in the bone, in particular during and after the orthopedic operation.
In respect of the prevailing level of technology in the field, reference is made mainly to the following patents: U.S. Pat. No. 5,156,616, U.S. Pat. No. 5,472,452 and U.S. Pat. No. 5,037,422.
In accordance with the suture anchor of patent U.S. Pat. No. 5,156,616, two separate sutures are inserted through a hole penetrating the body of the suture anchor in the longitudinal direction and situated substantially in the middle of the cross-section of the anchor body in a manner that the other ends of the sutures extend clearly outside the end at the base side of the suture anchor and the ends at the head side of the suture anchor are tied together, wherein the knot formed thereby prevents the suture from gliding through the hole, out from the suture anchor via its base. The suture anchor is provided with screw threads.
The suture anchor in accordance with patent U.S. Pat. No. 5,472,452 comprises a tubular body having a substantially quadrangular cross-sectional form, and a core part to be inserted therein. Two walls of the anchor body are provided with projecting branches which are pressed by the core part against the walls of a hole formed in the bone when the suture anchor is pressed into the hole. The branches are further provided with means which can be grabbed by a special tool, e.g. for moving the suture anchor inside the hole. The suture is arranged to circle outside the anchor body via two of its opposite vertical walls and heads. For implementation of this, the heads of said two vertical walls are provided with cuttings in which the suture is placed at the head of the anchor body.
The suture anchor of patent U.S. Pat. No. 5,037,422 is composed of a conical, hollow body which is positioned by pressing or hitting in a hole made in the bone. For keeping the anchor body in its place, it is provided with two splits situated substantially at the opposite walls thereof and having a cross-section parallel with the suture anchor, wherein the anchor body is contracted when inserted in the hole, tending to expand by pressing the gearing that is formed on the outer surface of the anchor body against the walls of the hole. The suture is positioned to travel substantially through the splits, parallel with them, and arranged to circle via a substantially straight, tubular turning portion situated in the vicinity of the head of the anchor body.
The suture anchor in accordance with the prior-mentioned patent U.S. Pat. No. 5,156,616 has a simple structure and comprises a screw-thread arrangement which is advantageous when placed in a bone. However, it is unsafe to keep the sutures tied in the suture anchor merely supported by said knot, and it is not possible to fully prevent the sutures from being damaged, in particular at the junction of the knot and the hole penetrating the suture anchor. Furthermore, a device installed in the base of the suture anchor for threading the suture anchor into the bone can damage the sutures, which are situated partially in a sleeve formed for the head of said device in the base of the anchor body.
The drawbacks of the two other solutions mentioned above (U.S. Pat. No. 5,472,452 and U.S. Pat. No. 5,037,422) are mainly related to the complexity in their structure and use. A particular drawback is that the suture channels through which the sutures are intended to be placed in the suture anchor are formed in a manner that harmfully abrupt alterations of direction take place, in particular adjacent to the heads of the suture anchors (an abrupt alteration of direction of about 90xc2x0) which easily results in partial breaking or even cutting off of the suture when the suture is tightened in a later phase of the orthopedic surgical procedure, because the suture is subjected to a strong tensile stress on its outermost surface.
The object of the invention is to introduce a suture anchor whereby the above-described shortcomings pertaining to known suture anchors can be eliminated to a great extent and thus the prevailing level of technology in the field can be elevated.
For achieving this object, the suture anchor according to the invention is characterized by a novel arrangement between the body of the suture anchor and the suture. This novel arrangement prevents the formation of abrupt alterations of course which add to the risk of damaging the suture. The body of the suture anchor consists of a single part, and the suture channel in which the suture is placed is entirely formed in the anchor body without any separate means and is composed of two longitudinal guides and a particularly curved turning portion which connects them. By means of this arrangement, in particular in view of the turning portion, the tensile strength of the suture required in the surgical operation can be maximally utilized. The primary characteristics of the suture anchor of the invention will be presented in the characterizing portion of the appended Claim 1.
The simple, substantially closed structure of the anchor body markedly adds to the strength of the suture anchor and thus also increases its operational reliability. The arrangements related to the suture channel also efficiently prevent the risk of damaging, which is present when bringing the suture anchor in the bone and which is particularly caused when the suture gets in contact with the surface of the bone of the drill canal.
The above-mentioned features and other features characteristic to the present invention, as well as embodiments of the invention will be presented in the accompanying dependent Claims.